A clone of Martha Jones was made by the Sontarans to infiltrate the United Nations Intelligence Taskforce. The clone had a mental link with the real Martha and could access her memories. If the link was broken, the clone would most likely not survive. The Sontarans used many clones to try to stop the Tenth Doctor from interfering with the conversion of the Earth's atmosphere and the subsequent invasion. The Doctor broke the link between Martha and the clone, killing it, but before it died, Martha used the fact that it still had some of her memories to convince it to help them. The clone explained that the ATMOS gas was clone feed. (TV: The Sontaran Stratagem / The Poison Sky)

In the far future, clones of Wolfgang Amadeus Mozart became hugely popular, not just for their musical talent but also used to perform menial duties. They were abandoned or thrown away after they became unfashionable. One clone time travelled to 1791Vienna to save Mozart's life and give him immortality, creating an alternate timeline in which Mozart lived long enough to become a hack. However, the clones were still mistreated in this timeline since enough people remembered the good music Mozart had written. The Sixth Doctor negated this timeline by persuading Mozart to refuse the clone's offer and destroying some of the pages of Mozart's final symphony, thus limiting the scale of Mozart's reputation so that the only clones that would be created were those that were genuinely wanted rather than to be part of the fad. (AUDIO: My Own Private Wolfgang)

Using DNA from the Fourth Doctor, a clone of the Second Doctor was produced. He believed that he was the Doctor, and even contained memories taken from the Doctor. However, he was in league with the enemies of the Doctor. The Fourth Doctor saved his life and he repaid him by helping return Hexford to its original place on Earth. Like the examples noted above, it was not believed to be able to last longer than a few months. (AUDIO: The Hexford Invasion, AUDIO: Survivors in Space)